Snap switch mechanism



May 1, 1962 J. T. PAYNE 3,032,621

SNAP SWITCH MECHANISNI 2 Sheets-Sheet 1 Filed May 19, 1959 a ma f May 1, 1962 J. T. PAYNE 3,032,621

' SNAP SWITCH MECHANISM 2 sheets-sheet 2 Filed May 19, 1959 Z225- BY@ Z647 rates The present invention relates to an improved electric snap switch mechanism.

A principal object of the invention is the provision of a snap switch comprising a pivoted contact arm shiftable between two switching positions lby a compression spring acting on the contact arm and shifted from one side to the other of a dead center position of the spring relative to the contact arm, in which position the springs force tending to shift the arm is zero, by a toggle member pivotally carried by an actuator movable transversely of the line of force of the spring and which toggle member is urged by the spring to rotate and move against the contact arm to thereby maintain the arm firmly in one switch position during movement of the spring through its dead center position.

Another object of the invention is the provision of a snap switch mechanism of the character described in the preceding paragraph in which the pivoted toggle member is limited in its movement in opposite directions about its pivot by a lost motion connection with the contact arm so that when the spring is shifted to snap move the contact arm it also snap shifts the toggle member and causes it to strike the arm with a hammer blow to augment the spring in shifting the arm, thereby insuring separation of the contacts of the switch although welding thereof may tend to occur due to high current passing therethrough.

It is a further object of the invention to provide a snap switch mechanism which can be constructed to occupy a relatively narrow space and yet provide a double throw contact arrangement having ample clearances for attaching leads to the terminals of the switch.

A still further object of the invention is the provision of a double throw switch mechanism having a beam type contact carrying arm formed of a spring sheet metal member reinforced along the sides thereof, the central portion of the arm being separated from the reinforcing means at the sides to form a llexible tongue which is attached to a suitable base to pivotally support the beam, each end of the beam having a contact engageable with a fixed contact respectively, and snap mechanism for shifting the beam on its flexible tongue.

Yet another object of the invention is the provision of a snap switch mechanism having a rigid main portion of a contact arm having a relatively flexible end portion carrying a contact so that the shock of the contact engaging another contact is absorbed without causing bouncing of the contact, and also on opening movement the flexing shears or pries the contacts apart in the event of any tendency to weld.

Other objects and advantages ofthe invention will be apparent from the following description of a preferred form thereof, reference being made to the accompanying drawings wherein FIG. 1 is a sectional view of an electric switch embodying the invention, the view being taken substantially along line 1-1 of FIG. 2 and showing certain parts broken away;

FIG. 2 is a sectional view taken substantially on line 2-2 of FIG. 1;

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2; e

FIG. 4 is an exploded view of certain parts of the switch, some of which are shown broken away; and

3,932,621 Patented May 1, 1962 FIGS. 5 and 6 are views similar to FIG. 2 but showmg certain parts of the switch in different positions.

' In the form of the invention shown, the switch mechanism is contained in an elongated, open top box-like housing 10, formed of a suitable dielectric moulded material, the top of which housing is normally closed by a cover 10a securedin place by screws 10b. It is to be understood that the switch could be mounted in any other suitable structure, if desired. The switching mechanism comprises a centrally pivoted contact arm or beam 11 having contacts 12 and 13 carried on opposite ends which alternately engage fixed contacts 14 and 15, located at opposite ends of the housing, when the beam is oscillated about its pivot, as described more fully hereinafter.

Beam 11 is preferably formed of a strip spring material having good electrical conducting properties, such as beryllium copper, and it includes a bottom wall 11a having turned up side walls 11b and 11c which lend rigidity to the beam. Preferably, these side walls terminate short of the ends of the bottom wall 11a so that the contact carrying positions of the wall may readily iiex relative to the beam proper. Wall 11a has a tongue 11d cut therefrom, which tongue is secured to a central terminal member 18, described more fully hereinafter so that the beam pivots on the tongue about a point indicated at A.

Terminal member 18 is centrally located on the bottom wall 10c of the housing and it comprises an inverted U-shaped bracket having legs 18a and 18b interconnected by a bridge-like yoke 18e to which tongue 11d is attached, and the legs project through slots in the bottom wall. Leg 18a projects well below the bottom wall and provides a blade type terminal connector, and leg 18b terminates just below the bottom wall. Legs 18a and 18b each has shoulders 18d and 18e which extend beyond the ends of the slots through which the legs project and engage the inside surface of bottom wall 10c to locate the terminal member on the wall. Each edge of legs 18a and 18b has tabs 181 which are bent outwardly against the under surface ofthe bottom wall of the housing to draw shoulders 18d and 18e to the inside of the bottom wall and thereby firmly anchor terminal member 18 in position.

Contacts 14 and 15 are attached to terminal members 19 and- 20, respectively, each of which comprises a yoke 19a, 20a and two sets of legs 19b, 20b and 19C, 20c which project through slots formed through the bottom wall of the housing. Legs 19b and 20b extend beyond the other leg of the respective terminal members and provide blade type terminal connectors, and the edges of these legs, as well as legs 19b, 20b, have tabs 19d, 20d, respectively, which are turned outwardly against the underside of wall 10c to draw the yokes of the terminal members iirmly to the bottom wall. Contact 14 is riveted to the top of yoke 19a and yoke 20a has a threaded opening through which contact 15 projects. Contact 15 comprises a threaded shank which is threaded through an opening through wall 10c and fits snugly in an opening through yoke 20a, and has a slot in the lower end to receive a screwdriver so that the height of contact 15 relative to the terminal member 20 can be adjusted, the purpose of which is explained hereinafter. When beam 11 is tiltedclockwise, as seen in FIG. 2, contact 13 engages contact 15 and contact 12 is separated from contact 14, and a circuit may be established through terminals 18 and 20. When beam 11 is rotated counterclockwise, contacts 13 and 15 are separated and contact 12 closes on contact 14 to establish a circuit through terminals 18 and 19. It will be seen that ample space is provided between the prong connector portions of the terminals so that leads may easily be attached or removed therefrom.

Beam 11 is moved about its tongue pivot by a spring 3 arm type actuator 22, also supported on yoke 18a, and the actuator includes a base portion 22a which rests on tongue 11d and is secured to the yoke, as is the tongue,

by a rivet 23. Both the actuator and tongue are notched Y at their ends to receive an upturned locating lug 24 formed on yoke 13a which cooperates with the sides of the notches to maintain the beam and actuator in place. Actuator 22 includes a depending bifurcatedend portion having spaced fingers 22h which are indented to form V pivot bearings, 22C. Actuator 22 preferably has a spherical formation 22d which provides a point of engagement with a dielectric actuating plunger 25, slidably guided in an opening through cover a. Actuator 22 is formed of a suitable spring material, such as beryllium copper, so that it can be relatively easily flexed and is normally biased to cause the left handl end thereof to spring upwardly, as seen in FIG. 6.

A snap mechanism is interposed between actuator 22 and beam 11 and it comprises an S-shaped compression spring 26, one end of which is pivotally connected with beam 11 and the other end of which is pivotally connected with a toggle member 27 pivotally carried on actuator 22. Beam 11 has an upturned end portion 11el which is notched at opposite sides, as may be seen in FIG. 4, to receive the forked end of spring-26, the portion between the notches being creased to form a V bearing 11] for the end of the springs. The notches and the forked portions received therein retain the end of spring 26 in engagement with portion 11e.

Toggle member 27 is formed of a rigid metal stamping in the form of a cross, including a neck 27a, arms 27b and a relatively lengthy stem 27C. Neck 27a projects through an opening in the right hand end of spring 26 to maintain the spring in engagement with the left hand edges of arms 27b, and the compression force of the spring urges the right hand edges of arms 27b into the indented bearing portions 22C of the actuator. Spring 26 is thus pivotally connected with beam 11 at point B and is pivotally connected with toggle member 27 aty point C. Toggle member 27 is pivoted to the actuator at point D.

Stern portions 27C projects between fingers 22b of the actuator and has a lost motion connection with beam 11 which is formed by the stern extending through an opening 11g formed in an upstanding lug portion 11h formed from the bottom wall 11a, the upper and lower edges of which opening provide spaced abutments 11j and 11k for limiting movement of toggle member 27 about its pivot D. It will be seen that the tension of spring 26 maintains the spring, toggle member and actuator in their assembled relationship.

When actuator 22 is in its depressed position, as shown in B1G. 2, pivot points C and D are below the dead center position of the spring and toggle member, which is on a straight line extending through points A and B, and the line of force of spring 26 acting on beam 11 is along line B, C which force urges the beam clockwise to close contact 13 on contact 15. Likewise, toggle member 27 is urged counterclockwise about pivot D to cause stem 27C to engage abutment 11j and urge the beam clockwise, urging contact 13 to contact 15. As button 25 is released, actuator 22 raises pivot D which causes toggle member 27 to pivot clockwise and bring pivot C in line with A, B at which point it is at dead center or equilibrium position with respect to beam 11 so that the force of the spring acting to urge the beam about its pivot is zero; however pivot D is above line B, C and the spring is urging the toggle counterclockwise about its pivot so that stem 27C maintains a clockwise bias on beam 11 to provide a substantial closing force on contacts 13, 15, although the force of the spring acting to rotate the beam is zero. Further upward movement of actuator 22` brings pivot C above the dead center line A, B whereupon the force of the spring urges beam 11 counterclockwisel and at substantially the same time line B, C shifts above pivot D which causes spring 26 to rotate the toggle member clockwise about D which snaps stem 27C from abutment 11j to 11k and thereby impart a hammer blow to beam 11 to urge the beam counterclockwise. At the same time, toggle member 27 further raises point C above line A, B to increase the component of spring force on.

beam i1 in a counterclockwise direction. The combination of the shifting of toggle member 27 from abutment 11j to 11k and the shifting of the line of force of the spring exerts a considerable force on the beam 11, including a hammer blow, to separate the contacts and this force will overcome tendency of the contacts to weld so that a positive switch operation is assured,

When button 25 is gradually depressed from the position shown in FlG. 6, pivot C is lowered to dead center line A, B so that spring 26 has a zero component with respect to beam 11; however, pivot D is above line AB so that toggle member Z7 is urged clockwise about D and thereby urges beam 11 counterclockwise to maintain a substantial contact pressure between contacts 12 and 14 until after pivot C is lowered beyond line A, B at which time the toggle member is snapped counterclockwise to strike abutment 11j and thereby cause positive shifting of beam 11 to the position shown in HG. 2. It will be seen that the same positive, snap movement is imparted to beam 11 on its counterclockwise movement as was the case of its movement in the opposite direction.

By adjusting the height of contact 15, the degree of throw of beam 11V can be controlled to thereby regulate the differential of movement required of actuator 22 to snap actuate the beam from one position to the other.

In forming the contact beam of a channel formation having the liexible tongue portion mounting and a contact attached at opposite ends, the switch mechanism cany be made exceedingly narrow and thereby provide a compact switching mechanism in which the terminals 1S, 19 and 2t) have maximum space separation, which facilitates the application of the leads to the terminals and also provides for safe electrical clearances. By terminating the stiffening side walls 11b, 11e short of the contact carrying end portions of beam 11, the contacts are carried on portions relatively flexible with respect to the beam proper so that a rolling or prying contact separation is provided which facilitates opening of the contacts in the event welding may tend to occur therebetween and also these flexible portions absorb shock of contact engagement to thereby prevent or minimize bouncing of the contacts upon engagement thereof with a fixed contact.

It will be seen that by my invention I have provided a relatively simple and compact switching mechanism which efficiently utilizes the forces applied in the actuation of the switch contacts so that a maximum current carrying rating for the switch can be obtained at a minimum of cost.

It is to be understood that while a preferred form oi the invention has been shown, it is understood that other forms, modifications and adaptations of the invention could be effected, all falling within the scope of the appended claims. v

I claim:

1. A snap switch including a contact arm, a pivot for said arm, means to lim-it movement of said arm about its pivot between two positions, an abutment on said arm, a compression spring engaging said abutment and disposed to shift its position to change the line of force thereof from one side to the other of a line through said pivot and the point of connection of said spring and abutment so as to snap said contact arm between said two positions, means to shift the position of said spring comprising an actuator, a toggle member pivoted on said actuator, said spring engaging said toggle member and exerting force in the direction of the pivot for said toggle member to tend to rotate said toggle member about its pivot in'one direction or the other, and means to [limit movement of said toggle member about its pivot including an abutment on said contact arm, the last mentioned abutment being movable with said contact arm and struck by said toggle member when said member is moved by said spring from one limit to the other, said actuator being movable to shift said actuator transversely of the line of force of said spring acting on said toggle member.

2. An electric snap switch comprising, a contact arm, means pivotally supporting said arm, a contact carried adjacent to one end of said arm, an abutment projecting laterally from said arm adjacent said end thereof, an actuator having a part movable in a direction transversely of the centerline of said arm, a toggle member pivotally carried by said actuator and having a part shiftable about the pivot of said toggle member in an arc extending generally parallel to the movement of said part of said actuator, and a compression spring interposed between said abutment and said shiftable part of said toggle member whereby said spring urges said toggle member about its pivot in either direction and reacts to urge said contact arm about its pivot in either direction according to the position of said part of said actuator.

3. In an electric switch mechanism, a contact arm, means pivotally supporting said arm, an end portion of said arm being formed at substantially right angles to said arm proper to provide an abutment, an actuator arm extending in spaced, substantially parallel relation with said contact arm and having an abutment spaced from the rst mentioned abutment, means pivotally supporting said actuator arm for movement of said abutment thereon toward and from said contact arm, a toggle member pivoted to said abutment on said actuator arm and having a part projecting toward the rst mentioned abutment, a compression spring interposed between said first mentioned abutment and said projecting part of said toggle member, said toggle member having a second part extending in the opposite direction from said rst mentioned part, and means forming a lost motion connection between said second part and said contact arm.

4. In a switch mechanism, a base member having two spaced contacts, a channel shape beam formed of resilient strip material, a tongue formed from the intermediate wall of said beam, means securing said tongue to said base at a point intermediate said fixed contacts and arranged for opposite end portions of said beam to overlie said contacts respectively, contacts carried on opposite end portions of said beam for engagement with said fixed contacts respectively when said beam is rocked on said tongue, a snap mechanism connected to said beam, said mechanism including an overcenter toggle member and a spring to snap said member in opposite directions, and an abutment on said beam to be engaged by said member during snap movement of said member in one direction.

5. A snap switch comprising a support structure, a fixed contact on said support structure, a contact arm pivotally attached to said structure and having a portion shiftable to and from said Contact, an abutment on said arm adjacent to the movable end thereof, stop means on said arm spaced inwardly relative to said abutment, an actuating member movable parallel to movement of said contact arm and having a part lying intermediate said abutment and stop means, a toggle member pivoted on said part and having a c .-ction projecting toward said abutment and a second section extending to said stop means and cooperating with said stop means to provide a lost motion action between said toggle member and stop means in a direction parallel to movement of said contact arm, and a compression spring having one end engaging said abutment and the other end engaging said lirst mentioned section of said toggle member and exerting a force on said toggle member tending to rotate said member in one direction or the other about said pivotal connection with said actuator.

6. A switch mechanism as defined in claim 4 in which the sides of said channel-shaped beam terminate short of the end portions carrying said contacts carried thereby.

References Cited in the file of this patent UNITED STATES PATENTS 2,228,523 Johnson Jan. 14, 1941 2,556,216 Raney Jan. 12, 1951 2,688,058 Perkins Aug. 31, 1954 2,748,214 -Immel May 29, 1956 2,767,270 Perkins Oct. 16, 1956 2,821,588 Fisher Ian. 28, 1958 FOREIGN PATENTS 538,317 Great Britain `Tuly 29, 1941 985,619 France Mar 14, 1951 

